1. Field of the Invention
The present invention relates to cooking with the use of microwave, and more particularly to a method of heat-gelled foods, dried instant foods and cooking thereof, liquid foods and heating thereof, and heating tools for a microwave oven.
2. Discussion of the Background
Recently, microwave ovens both for commercial and domestic uses are popularized and utilized for convenient cooking as cooking devices wherein heating can be done for a short time.
Therefore, also in cooking for foods to be gelled by heating such as Japanese food chawanmushi, Japanese food odamakimushi, pudding, Japanese food tamagodofu and the like, the microwave oven heating has been utilized in place of heating by means of the conventional steam heating or the like.
However, even though it being said as microwave oven heating, if a steam cup (mushi-jawan) which has been filled with the raw material containing egg prior to gelation (referred to as "egg liquid" in this specification) is covered with a lid, placed in a microwave oven, and heated desultorily, there is a tendency to produce so-called honeycomb hollows on the surface of the gelled egg liquid because of localized overheating on the surface layer of the egg liquid. Thus, in order to prevent it, it is known that the surface of an egg liquid is covered with an aluminum foil to prevent the localized overheating of the egg liquid and make the whole egg liquid to be heated uniformly as possible, and then it is heated in a microwave oven. In this case, it may be carried out to introduce water around the cup.
However, as to the said method wherein the aluminum foil or the aluminum foil with holes is used to prevent localized overheating and make the whole egg liquid to be heated uniformly as possible and prevent production of the honeycomb hollows, it can be realized in a low-power domestic use microwave oven with an output of about 500-600 W for a prolonged time, but in the case of a high-power commercial use microwave oven with an output up to 1400-1600 W, honeycomb hollows and uniform heating of the egg liquid in the vessel are caused owing to partly insufficient heating (particularly, at the center of the surface) or overheating (around the surface) resulting from temperature increase for a very short time.
Therefore, it is required to develop an effective method of heating evenly and uniformly when gelled foods are prepared by heating in the microwave oven, particularly in the commercial use microwave oven.
Under the above-mentioned technical background, it is an object of the present invention to provide an uniform heating method for effective prevention of honeycomb hollow occurrence, when the gelled foods are produced by gelling the liquid raw material by means of microwave heating, particularly commercial use microwave heating.
As has been described above, recently, microwave ovens both for commercial and domestic uses have been popularized and utilized in convenient cooking as cooking devices capable of heating foods in a short period of time.
And, as a way of such utilization, it is considered to cook them by placing a dried instant food such as dried instant noodle, dried porridge, dried powdery miso soup, dried soup or dried red-beam soup (they may of course be packed in a cup like cup noodle or cup soup), together with water in a vessel, apply stirring if necessary (particularly in a case of powdery foods), and heating them with a microwave oven. This procedure is much convenient since a step of separately boiling water can be saved.
However, in a case of actually cooking a dried instant food in a microwave oven, since the contents in the vessel are difficult to be heated uniformly and it is often experienced that the upper part of the contents has been already well cooked by being heated to such an extend as suitable to eat but the part at the bottom of the vessel has not yet been heated sufficiently and reversion of the dried instant food is insufficient. Further, in a case of powdery soup containing a proteinous raw material, if it is placed in a cup, added with water and warmed in a microwave oven, it is often experienced as well that, due to localized overheating of the surface, heat-coagulated membranes of protein are formed on the surface of the liquid contents, or the contents deposit on portions adjacent to the vessel wall.
As has been described above, cooking of dried instant foods by using the microwave oven can provide a merit of allowing convenient cooking but entails a problem that uniform heating is difficult or causing localized overheating.
Under the above-mentioned technical background, it is another object of the present invention to provide means capable of uniformly heating the contents in a vessel and means capable of effectively preventing localized overheating upon heat-cooking of dried instant foods together with water in a microwave oven.
Again, as has been described above, recently, microwave ovens both for commercial and domestic uses have been popularized and utilized in convenient cooking as cooking devices capable of heating foods in a short period of time.
Such a way of utilization includes, for example, warming Japanese sake contained in a sake bottle (tokkuri) with a microwave oven or warming milk filled in a cup with a microwave oven into hot milk.
However, in a case of heating with a microwave oven it is often experienced that such a situation in which the lower part of the liquid contained in a vessel is not yet heated sufficiently and tepid although the upper part thereof has been sufficiently heated to an appropriate temperature or, on the contrary, the upper part becomes too hot when the lower part is heated to a moderate temperature, failing to attain uniform heating. In addition, if such foods not heated uniformly are taken as they are, it is extremely uncomfortable, for example, in that milk which is initially at a moderate temperature gradually becomes tapid and, further, turns cold.
Further, if the sake bottle is warmed by using a microwave oven, sudden boiling is often caused due to the overheating of the surface part. Sudden boiling deteriorates the sake in taste and, further contaminates the inside of the microwave oven as well. Furthermore, when milk contained in a cup is warmed with a microwave oven, it is often experienced that membranes caused by heat-coagulation of protein are formed on the surface of the milk, or heat-coagulation products of the protein deposit on portions of the surface in contact with the cup wall, owing to the overheating of the surface part.
As described above, when liquid foods are heated with a microwave oven, it is difficult to uniformly heat them to a moderate temperature, which sometimes results in a problem, for example, sudden boiling or deposition of heat-coagulation products due to a not-uniform heating or localized overheating.
Under the above-mentioned technical background, it is a third object of the present invention to provide means capable of uniformly heating liquid foods to a moderate temperature and effectively preventing sudden boiling or deposition of heat-coagulation products caused by localized overheating upon heating the liquid foods with a microwave oven, as well as liquid foods packed in a vessel equipped with such means for microwave heating.
Under the above-mentioned technical background, finally, it is an object of the present invention to provide uniform heating tools for effective prevention of honeycomb hollows, when gelled foods are to be produced by gelling a liquid raw material by means of microwave heating, particularly, by using a commercial use microwave heating, tools capable of uniformly heating the contents in a vessel and effectively preventing localized overheating upon heat-cooking of dried instant foods together with water in a microwave oven, and tools capable of uniformly heating liquid foods to a moderate temperature and effectively preventing sudden boiling or deposition of heat-coagulation products caused by localized overheating upon heating the liquid foods with a microwave oven.